Conventionally, a known position sensing device is configured to detect a movement of a vehicular device. For example, such a known position sensing device is configured to detect a rotation angle of a throttle valve equipped in an electronically controlled throttle device for a vehicle, a rotation angle of an accelerator pedal equipped in an accelerator pedal module, a rotation angle of a tumble control valve, and/or a stroke quantity of a clutch actuator. For example, a position sensing device used for an electronically controlled throttle device is configured to output a voltage signal, which indicates an opening position of a throttle valve, to an electronic control unit (ECU). In this case, the ECU outputs a driving signal to a motor to drive the throttle valve according to the voltage signal such that the opening position of the throttle valve coincides with a target opening position suitable for an operation state of an internal combustion engine. Thus, the motor controls the opening position of the throttle valve at the target opening position in this way, thereby to control an amount of intake air supplied to the internal combustion engine.
In such an electronically controlled throttle device, a fail-safe design is required to enable a safe control of the throttle valve when the position sensing device has a malfunction.
US Patent Application Publication US 2001/0004213 A1 (JP Patent 3491587) discloses a position sensing device including two hall IC devices for detecting a rotation angle of a throttle valve. The two hall IC devices have the same output characteristics in which the output voltage increases as the opening (opening position) of the throttle valve becomes large. In the present configuration of US 2001/0004213 A1, when one of the two hall IC devices has a malfunction, the other of the hall IC devices is capable of controlling the opening of the throttle valve.
To the contrary, U.S. Pat. No. 5,260,877 (JP Patent 3588127) discloses a position sensing device including two potentiometers having output characteristics different from each other for detecting a rotation angle of a throttle valve. In the present configuration of U.S. Pat. No. 5,260,877, an output voltage of one of the two potentiometers increases, as an opening of a throttle valve becomes large. In addition, an output voltage of the other of the two potentiometers decreases, as the opening of the throttle valve becomes large. In the configuration of U.S. Pat. No. 5,260,877, a circuit of the one potentiometer is connected with a pull-down resistor element, and a circuit of the other potentiometer is connected with a pull-up resistor element.
It is noted that when the electronic control throttle is equipped with, for example, two potentiometers having different output characteristics (different operations) when the power supply voltage decreases or two hall IC devices, there is a concern that the number of components increases to raise the manufacturing cost.